1. Field of the Invention
The present invention relates to confectioneries and their methods of preparation. Improving the packing of solids-containing ingredients provides the confectioneries of this invention having a total fat content of about 16% to about 35% by weight and with desirable rheology characteristics. The confectioneries of the present invention demonstrate good performance when used in enrobing, moulding or extruding operations.
2. Related Background Art
Confectionery food products, made from ingredients including carbohydrate sweeteners, such as sucrose, milk solids, cocoa solids and an edible oil or fat, such as cocoa butter, are well known. Candy, and particularly chocolate, comprise an important group of these food products.
The most popular chocolate or chocolate candy consumed in the United States is in the form of sweet chocolate or milk chocolate. Chocolate is a dispersion of very fine, solid ingredient particles suspended in a fat phase. Milk chocolate is a confection which contains milk solids, milk fat, chocolate liquor, a nutritive carbohydrate sweetener, cocoa butter and may include a variety of other ingredients such as emulsifying agents, flavorings and other additives. Crumb chocolate is a type of milk chocolate wherein wet milk and carbohydrate sweetener ingredients, and optionally chocolate liquor, are pre-combined then co-dried, at elevated temperatures, to form a milk crumb. The milk crumb is then used to prepare this type of milk chocolate. Sweet chocolate contains higher amounts of chocolate liquor, but lower amounts of milk solids than milk chocolate. Semi-sweet chocolate requires at least 35% by weight chocolate liquor and is otherwise similar in definition to sweet chocolate. Dark chocolate, generally containing only chocolate liquor, a nutritive carbohydrate sweetener and cocoa butter, is by definition either a sweet chocolate or a semisweet chocolate. Buttermilk chocolate and skim milk chocolate differ from milk chocolate in that the milk fat comes from various forms of sweet cream buttermilk and skim milk, respectively. Skim milk requires the total amount of milk fat to be limited to less than the minimum for milk chocolate. Mixed dairy product chocolates differ from milk chocolate in that the milk solid includes any or all of the milk solids listed for milk chocolate, buttermilk chocolate or skim milk chocolate. White chocolate differs from milk chocolate in that it contains no non-fat cocoa solids.
Chocolate may take the form of solid pieces of chocolate, such as bars or novelty shapes, and may also be incorporated as a component of other, more complex confections where chocolate is combined with and generally coats other foods such as caramel, peanut butter, nougat, fruit pieces, nuts, wafers, ice cream or the like. These foods are characterized as microbiologically shelf-stable at 65xc2x0-85xc2x0 F. (18-29xc2x0 C.), under normal atmospheric conditions. Generally, chocolate used to coat or surround foods must be more fluid than chocolates used for plain chocolate solid bars or novelty shapes.
The process of coating chocolate onto a food is known as enrobing. Enrobing is accomplished when chocolate, in a fluid state and having a proper viscosity and yield value, is poured over a food to completely cover the food. Alternatively, the food may be dipped into the fluid chocolate. Proper viscosity and yield value of the chocolate are required for smooth and even flow of the chocolate over the surface of the food to be coated.
Chocolate can also be moulded. By moulding, it is meant that chocolate, either plain or mixed with nuts, raisins, crisped rice and the like, is deposited in moulds, allowed to cool and hardened into solid pieces and then removed from the mould. Chocolate moulded into plain chocolate pieces may be somewhat more viscous than coating chocolates since the chocolate can be vibrated into a mould over a longer period of time than allowed in enrobing.
Novelty shapes, such as chocolate chips, made of plain chocolate may be formed by extrusion, typically onto a cold belt. Extrusion may also be conducted using chocolate in a solid or semi-solid state. Other forming techniques known in the art include flaking, kibbling, sheeting, depositing and the like. The chocolate used for extrusion must be more resistant to flow than chocolate used for moulding and have a high yield value. Chocolates used in extruding operation typically will have yield values of less than 600 dynes/cm2 and plastic viscosity values of less than 100 poise. The relatively high viscosity and yield value are necessary for the chocolate to retain the extruded shape as it hardens.
Since melted chocolate is a suspension of solid particles, e.g., sugar, milk powders and cocoa solids, in a continuous liquid fat phase of cocoa butter, chocolate suspensions have non-Newtonian flow behavior including the presence of a yield stress. The yield stress represents a minimum threshold of force that must be applied to a suspension, for example the force applied to toothpaste, in order to make it flow. Below this threshold, no flow occurs. The non-Newtonian behavior of chocolate is sometimes described by fitting the rheological data to the Casson equation which defines a Casson yield value and Casson plastic viscosity. This minimum force mentioned above is then referred to as the xe2x80x9cCasson yield valuexe2x80x9d. The xe2x80x9cCasson plastic viscosityxe2x80x9d approximates the work needed to keep the suspension flowing uniformly. Alternatively, an apparent viscosity can be used to describe the flow behavior of chocolate. The rheological characteristics of chocolate, and the ability to maintain control over the rheology of chocolate are very important. Chocolate is a suspension of very fine particles (usually less than 50-60 microns) in fat (cocoa butter, milk fat). The cocoa butter coats and suspends the particles and provides the mouthfeel typically associated with a smooth, rich chocolate. The amount of cocoa butter present in chocolate affects the rheological properties of the chocolate and, consequently, must be varied according to the intended use of the chocolate. However, when the cocoa butter (fat) content of chocolate is reduced to prepare reduced-fat chocolates, alternate means of achieving the proper rheological properties of the chocolate must be developed. Emulsifiers, e.g. lecithin, have long been used to enhance the rheological properties of commercial chocolates. Exemplary emulsifiers include lecithin derived from vegetable sources such as soybean, safflower, corn, etc., fractionated lecithins enriched in either phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl inositol or any combination, mono- and di-glycerides, phosphated mono- and di-glycerides/diacetyl tartaric acid esters of mono- and di-glycerides (PMD/DATEM), monosodium phosphate derivatives of mono- and di-glycerides of edible fats or oils, sorbitan monostearate, polyoxyethylene sorbitan monostearate, hydroxylated lecithin, polyglycerol esters of fatty acids, polyglycerol polyricinoleate (PGPR), propylene glycol mono and di-esters of fats and fatty acids, and the like.
The addition of about 0.1-0.3% by weight soy lecithin typically reduces the viscosity of chocolate by more than 10 times its own weight of cocoa butter. Numerous other emulsifiers similarly lower the yield value or the plastic viscosity. Emulsifier use has generally been limited to less than 1% by weight of the chocolate formulation due to problems such as off-flavors, legal controls, or negative rheological effects occurring at higher use rates. Since full-fat chocolates, having about 25% to 36% by weight total fat, typically contain about 0.1% to about 0.5% by weight soy lecithin, significantly lower fat levels cannot be achieved by merely altering the amount of emulsifier incorporated into the chocolate.
Particle size of the non-fat solid ingredients is also known to influence the viscosity of chocolate. Generally, as the particle size of the solids-containing ingredients decreases, viscosity increases. Moreover, it is also recognized that particles below 5 microns will make the chocolate extremely thick and difficult to manage during pumping, depositing, and enrobing operations. Conversely, use of coarse particles of the solids-containing ingredients will decrease viscosity. However, coarse particles having a particle size greater than 60 microns will give the chocolate an unacceptable gritty sandy texture.
The presence of fines (or ultra-fine) particles are considered to adversely influence the rheological properties of chocolate. At least 50% of the surface area of milk chocolate solids is thought to be from particles below 2 micron in size. U.S. Pat. No. 5,080,923 discloses dissolving ultra-fine particles and recrystallization onto larger sucrose particles to reduce the total surface area of the solids-containing ingredients. This process however, provides chocolates having unacceptably high viscosity values as the fat content is reduced to near 20%. Plastic viscosity values related to the amount of work required to keep a chocolate suspension flowing. PCT International Publication No. WO 96/19923 discloses a process for producing chocolate with a total fat content between 18% to 24.9% by weight. Less than 1% by weight of the particles of this chocolate would have a diameter above 60 microns and not more than 20% by weight of the particles would have a diameter less than 3 microns.
The high solids content of chocolate has prompted some workers to examine the particle size distributions present in manufactured chocolates. Much of the work reported in the literature relies on one of two assumptions for particle packing: first, that particles have a discrete size and second, that particles are in a continuous distribution. Two approaches developed for the study of particle distributions, and used in the method of the present invention, are the discrete particle approach and the continuous distribution approach.
The discrete particle approach idealizes particle packing as a function of the diameter ratio of two or more discrete sizes of particles. A bi-modal particle distribution is characterized by a particle distribution having two separate and essentially non-overlapping particle distributions. Typically, there are particles with two discrete sizes: a coarse size, and a fine size having a size about {fraction (1/10)} the coarse size. The continuous distribution approach idealizes particle packing based upon the concept that improved packing occurs when a well defined concentration of particle sizes are used between the largest and smallest particles in a distribution.
The packing of particles has both practical and theoretical interest in a number of disciplines not related to confectioneries, for example, in the ceramics and paint industries. Cheng et al., (Journal of Material Science 25, 353-373 (1990)) investigated the effect of particle size distributions on the rheology of dental composites. Narrow sized fine (0.2 microns), medium (1.7 microns), and coarse (25.5 microns) particle fractions were blended into bi-modal and tri-modal distributions. Minimum viscosity was predicted for bi-modal blends when 20% to 40% by weight of the solids was a small size. U.S. Pat. No. 4,567,099 describes the use of a bi-modal particle size distribution to prepare high solids content latex paper coatings.
Bierwagen and Saunders (Power Technology, 10, 111-119 (1994)) quantitatively studied the effects of particle size distribution on particle packing for paint pigments. Very high packing efficiencies were possible when particle distribution modes were very dissimilar. This is the effect of packing small particles in the interstices of larger particles. Continuous distributions had maximum packing when the concentration of the coarse sized distribution was between 60 and 80%, by weight, of the total solids.
Dinger and Funk (Predictive Process Control of Crowded Particulate Systems Applied to Ceramic Manufacturing, Kulwer Academic Publishers (1994)) derived the following Equation (1) to determine the cumulative percent of particles in a continuous distribution that is finer than a specified particle size (CPFT), based on the Andreasen packing theory, with an added term to account for the smallest particles in the distribution.                               CPFT                      100            ⁢            %                          =                                            D              n                        -                          D              s              n                                                          D              L              n                        -                          D              s              n                                                          Eqn        .                  xe2x80x83                ⁢                  (          1          )                    
DL=the diameter size of the largest particle in the distribution
Ds=the diameter size of the smallest particle in the distribution
D=a selected particle size in the distribution
n=numerical exponent, with n being in the range of about 0.2 to about 0.7.
Funk, U.S. Pat. Nos. 4,282,006 and 4,477,259, the disclosure of which is incorporated herein by reference, applied this equation to the problem of transport of coal/water mixtures.
Milk chocolate is a concentrated suspension of sucrose, cocoa solids and milk solids dispersed in cocoa butter and milk fat. Chocolate is typically 25% to 36% total fat, by weight. Stated in another manner, chocolate is a suspension of solids in a fat containing 0.64-0.58 volume fraction of solids. Fischer (xe2x80x9cParticle Size Distribution Effect on Rheology of Molten Dark Chocolate,xe2x80x9d M. S. Thesis, Pennsylvania State University (1994)) prepared a set of dark chocolates having 25% total fat, by weight. The solids-containing ingredients for each chocolate were selected to have a narrow uni-modal, wide uni-modal, or bi-modal particle distributions, having the same relative mean diameter. The plastic viscosity of these samples decreased as the particle size distribution became xe2x80x98widerxe2x80x99. The bi-modal distribution sample demonstrated the lowest plastic viscosity, but the highest yield value. Fischer concluded that the advantage of the bi-modal approach could only be utilized where a higher yield value could be tolerated.
Mongia and Ziegler (xe2x80x9cParticle Size Distribution Affects the Rheology of Milk Chocolate,xe2x80x9d presented at Fine Powders Processing 1997, Sep. 15, 1997, Pennsylvania State University) studied the effect of particle size distribution on suspension rheology for a milk chocolate coating at 27.7% by weight total fat, prepared by blending coarse sugar fractions with finely ground sugar, milk and defatted cocoa powder. The Casson viscosity was shown to decrease for the mixtures of coarse and fine ingredient blends and to reach a minimum at 50% coarse concentration. The ratio of particle sizes in the coarse and fine fractions was about 2:1. The yield value had a linear dependence on mean particle size and the lowest apparent viscosity was obtained when the coarse fraction was between 65% to 70% by weight of the total solids mixture.
As described above, chocolate is a highly concentrated suspension of solids-containing ingredients in fat and research has indicated that the particle packing of the ingredient mixture can affect the rheology of the final chocolate. Although some progress has been made to better understand and improve chocolate rheology, further improvements are required to more predictably control the viscosity and yield value of chocolate. Moreover, such improvements are necessary to provide chocolates that have useful rheological properties and full-fat texture, that are very low in fat, e.g., with total fat content below 20% by weight.
This invention relates to a chocolate, having about 16% to about 35% total fat, by weight, having low viscosity and other rheological properties required for enrobing, moulding or extruding operations. A particularly preferred embodiment relates to a reduced-fat chocolate, having about 16% to about 24.5% by weight total fat and having suitable viscosity and other rheological properties required for enrobing, moulding or extruding operations. The invention further relates to novel methods for making the chocolates of this invention.
A confectionery of this invention comprises an admixture of solids-containing ingredients and fat, having a yield value of less than 1000 dynes/cm2, wherein said solids-containing ingredients have a bi-modal particle distribution and comprise particles having a diameter of about 0.05 microns to about 100 microns. The bi-modal particle distribution contains a fine particle mode distribution containing particles having a mean particle size of about 0.5 to about 7 microns, and a coarse particle mode distribution containing particles having a mean particle size of about 15 to about 50 microns. The particles in the fine particle mode distribution contain about 20% to about 40% by weight of the solids-containing ingredients and the particles in the coarse particle mode distribution contain about 60% to about 80% by weight of the solids-containing ingredients, based on the weight of de-fatted ingredients. In another embodiment, a confectionery of this invention comprises an admixture of solids-containing ingredients and fat, containing about 16% to about 35% by weight total fat and having a yield value of less than 1000 dynes/cm2, wherein the solids-containing ingredients comprise particles having a particle size distribution of about 0.05 microns to about 100 microns, and have a particle size distribution in accordance with the following formula:       CPFT          100      ⁢      %        =                    D        n            -              D        s        n                            D        L        n            -              D        s        n            
wherein,
CPFT=cumulative percent of particles in a continuous distribution having a particle size finer than a specified particle size;
DL=the largest particle diameter size in the distribution;
Ds=the smallest particle diameter size in the distribution;
D=a particle size in the distribution;
n=about 0.2 to about 0.7.
The solids-containing ingredients having a particle size of about 0.05 microns to about 30 microns may be selected from cocoa solids-containing ingredients, carbohydrates, milk solids-containing ingredients and ingredient combinations thereof, and preferably, may be cocoa solids-containing ingredients and/or milk solids-containing ingredients. The solids-containing ingredients having a particle size of about 30 microns to about 100 microns may be selected from cocoa solids-containing ingredients, carbohydrates, milk solids-containing ingredients and ingredient combinations thereof.